1. Technical Field
The present disclosure relates to hair conditioners and 2-in-1 conditioning shampoos.
2. Background of Related Art
Hair conditioners are widely known and used to impart desirable attributes to human hair. For example, hair treated with conditioners is noticeably smoother and softer to the touch. Additionally, hair conditioners render the hair more rinsable and impart a greater ease of detangling and greater manageability to combing, brushing, and styling.
Cationic surfactants and quaternary ammonium compounds have been used in personal care products to improve the appearance, feeling and health of the treated hair. Cationic surfactants are those in which the surfactant activity resides in the positively charged cation portion of the molecule. The cationic surfactants are therefore attracted to the negatively charged hair surface and, because of their relatively low solubility and high molecular weight, are thermodynamically driven to leave the aqueous environment of the shampoo and deposit on the hair. These characteristics make cationic surfactants such as quaternary ammonium compounds particularly suited to the treatment of human hair. Thus, many hair conditioning products are based on quaternary ammonium compounds.
Such compounds can have one, two, or three long chain alkyl groups attached to the nitrogen head group. Typically, long chain alkyl groups comprise chain lengths of from about 12 to about 24 carbon atoms.
The ability to soften hair and reduce static charge build-up is typically a function of both the carbon atom chain length and the number of chains attached to the nitrogen head group. Generally, the longer the carbon chain and the greater the number of chains the greater the lubricity of the shampoo and static charge neutralization. However, the chance of the hair "matting" and acquiring a greasy and heavy look also increases.
Hair conditioners have often been separate from the shampoo. However, the desire by the consumer for the convenience of personal hair care products having both cleaning and conditioning functions in the same product has increased. Such products are known as 2-in-1 conditioning shampoos. These contain both cleaning and conditioning surfactants. Such conditioning shampoos clean soiled hair and leave a conditioner in the hair at the same time. Thus, it is unnecessary for the consumer to subsequently use a conditioner after using the shampoo.
However, cleaning surfactants are typically anionic, i.e., the surfactant activity resides in the negatively charged anion. Anionic and cationic surfactants are usually incompatible, forming a complex which precipitates from the solution when mixed. It is important that the correct surfactants be employed to prevent interference between the negatively charged cleaning surfactants and the positively charged conditioning surfactants.
One way of accomplishing this is to choose the cationic surfactant such that the positively charged quaternized nitrogen is sufficiently shielded from the negatively charged surfactants and raw materials present within the conditioning shampoo mix. This can be done by using trialkyl quaternary ammonium compounds. Such compounds are known in the art but are difficult to produce and require large amounts of energy and time. Moreover, they degrade relatively slowly in the environment.
What is needed is a formulation providing an effective biodegradable conditioner in a cleaning shampoo at minimal cost.